Hello Guest!
Welcome to the official Square Foot Gardening Forum.
There's lots to learn here by reading as a guest. However, if you become a member (it's free, ad free and spam-free) you'll have access to our large vermiculite databases, our seed exchange spreadsheets, Mel's Mix calculator, and many more members' pictures in the Gallery. Enjoy.

Sounds like you have enough drainage holes in place. I found a posting by Boffer using the search feature under Table Top"For beds 4x4 and smaller, the simplest solution is to attach a piece of 3/4 inch plywood, with a couple 1/4 inch drain holes in each square, to the bottom of your box"2 X 8 would have the same surface and volume as 4 X 4, so I think you are fine.

I have seen women looking at jewelry ads with a misty eye and one hand resting on the heart, and I only know what they're feeling because that's how I read the seed catalogs in January - Barbara Kingsolver - Animal, Vegetable, Miracle

I have 2, 2x8 ft gardens in my garage (heated) this winter. I have 3/8" plywood for the base, and currently have 1/4" holes every 4 inches or so. I'm wondering if this is enough for drainage?

Thanks,

John

Howdy John:

According to the book, "ALL NEW Square Foot Gardening", Mel recommends one 1/4 inch hole for each square plus an extra in each corner of the box. You are on the right path. In my TT boxes I have used the 12 inch rule on some and on others I have them every 8 inches or so and all are working great. Also on some of my "salvaged" table top boxes the water drains around the sides so no extra holes were needed.